Load lifting apparatus



y 1966 w. w. GRIDLEY LOAD LIFTING APPARATUS Filed Nov. 12, 1964 Y E m mmW m %m 5 W m w m m U n m m w B O A m United States Patent 3,259,369 LOADLIETING APPARATUS William W. Gridley, The Ready-Lift Mfg. Co, 341 E.Leap Drive, Camariilo, Calif. Filed Nov. 12, 1964, Ser. No. 410,806Claims. (Cl. 254-122) This invention relates generally to load liftingapparatus and more particularly to a portable hoist which may be usedindoors or outdoors for elevating materials and equipment together withmen to locations adjacent work ing areas.

At the present time, particularly in the residential and industrialconstruction trades, it is oftentimes necessary to raise heavy materialssuch as beams, girders, roofing materials, and the like to aconsiderable height above the ground level for their use in the upperportion of the structure being built. While elevators and other types ofhoisting equipment are available and used in connection with multi-storybuilding and larger industrial buildings, the need has arisen for asimple portable hoist which may be used with conventional one or twostory homes and smaller business properties. In fabricating suchbuildings, most contractors at the present time use manual power orimprovised pulley arrangements as a means of lifting materials to properpositions for fabricating roofs or forming the second story ofbuildings.

In my United States Patent No. 3,003,746 patented October 10, 1961, andentitled Load Lifting Apparatus there is disclosed and claimed aportable hoist or load lifting apparatus which fully conforms to theforegoing requirements. Essentially, this structure as described in thepatent provides first and second frames including crossed leversinterposed between the frames adapted to execute scissor-like action toexpand or contract the fbames away or towards each other. The upperframe constitutes a platform and the lower frame a base support whichmay be provided with castors.

In the foregoing structure, there is provided an hydraulic ram meanscoupled between two vertices of a parallelogram portion defined by thecrossed levers when the upper frame is partially extended to effectraising and lowering of one frame relative to the other. With theparticular structure described in this patent, the degree of collapsingis somewhat limited as a consequence of the positioning of the hydraulicram for actuating the structure.

With the foregoing in mind, it is accordingly a primary object of thepresent invention to provide a load-lifting apparatus which provides allof the various advantages of the apparatus described in my abovereferred to patent and in addition provides a structure capable ofcollapsing to a substantially fiat configuration, all to the end that amore compact structure when in a collapsed position is provided.

More particularly, it is an object of this invention to provide animproved coupling arrangement for connecting hydraulic or otherexpansible ram means to a crossed lever structure in a portable hoist,so designed as to reduce the travel of the ram means without changingthe travel of the crossed lever structure and permit collapsing to aflat condition without interference with the crossed lever structure.

Other objects of this invention are to provide an improved load liftingapparatus which is rugged in construction, economical to manufacture andoperate, and easy to move about to convenient locations both indoors andoutdoors for elevating materials and equipment to various working areas.

Briefly, these and many other objects and advantages of this inventionare attained by providing basic frame structures with crossed leversinterposed therebetween in a manner similar to that described in myabove mentioned 3,259,369 Patented July 5, 1966 United States Patent3,003,746. However, in accordance with the instant improvement, theexpansible ram means for powering the structure to raise the samebetween collapsed and extended positions is coupled at one end to anovel drive bar structure and at its other end, to one of the crossedlevers. The drive bar structure itself is coupled to opposite sides ofthe central parallelogram portion defined by the crossed levers, thepoint of connection to the expansible ram means being displaced from astraight line drawn between the coupling points of the drive bar. Bythis arrangement, the travel of the ram means: is reduced and thecrossed levers may collapse to a substantially flat configuration withthe displaced coupling point on the drive bar extending either below orabove the configuration when in flat condition. There is thus avoidedinterference between the expansible ram means and its coupling structurefrom the crossed levers proper so that substantially complete collapsingof the levers can take place.

A better understanding of the invention will now be had by referring toan illustrative embodiment thereof as shown in the accompanyingdrawings, in which:

FIGURE 1 is a perspective view of the load lifting apparatus of thisinvention illustrating the crossed lever structure in partially extendedposition;

FIGURE 2 is a side elevational view illustrating the apparatus in FIGURE1 in its completely collapsed position; and,

FIGURES 3, 4, 5, 6, and 7 are schematic diagrams of the crossed leverarrangement shown in FIGURE 1 illustrating various optional locationsfor the expansible ram means employed to operate the structure.

Referring first to FIGURE 1 there is illustrated a first frame structure10 which may be provided with castors t1. Mounted on the frame structure10 is a crossed lever arrangement designated generally by the numeral12. A second frame member or platform 13 is disposed at the upper end ofthe crossed levers. The lever arrangement is such that a portion of thelevers defines a parallelogram shape with the lever ends extendingdownwardly and upwardly to engage the first and second frames 10 and 13as illustrated. Thus, lower lever ends 14 are pivoted to the first frame10 at the rear portion thereof as by pivot rod 15. The other ends of thelevers 14 are pivoted at 16 to levers 17. The upper ends of levers 17 inturn are pivoted as by pivot rod 18 to the rod portion of the upperframe 13.

Similarly, another set of levers 19 have their lower extending endsterminating at the front portion of the frame iii in rollers 20 so thatthe ends of these levers may move horizontally away from or towards thepivot rod 1 5 for the levers 14'. The upper ends of the levers 19 arepivoted by the rod 2-1 to lever-s 22. The other ends of the levers 22 inturn similarly terminate in rollers 28 adapted to roll along theunderside of the upper frame 13 so that these ends may \movehorizontally away from or towards the pivot rod 18 for the levers '17.

The crossover points for the levers 14 and 19 are pivoted together bypivot rod 24 forming a lower vertex of the central parallelogram portiondefined by the crossed levers, and the upper levers 17 and 22 arepivoted together at their crossover points as by pivot rod 25 at theupper vertex of the parallelogram portion.

From the arrangement described thus far it will be evident that thecrossed levers are free to collapse in scissoring fashion so that theplatform or upper frame 13 may engage the lower frame 10 with thecollapsed lever structure lying in a substantially flat configuration.

In order to actuate the crossed levers to raise and lower the upperframe 13, the-re is provided an expansible ram means preferablyhydraulically operated in the form of hydraulic ram means 26. Inaccordance with .the present invention, one end of the ram means 26 iscoupled to a pivot bar point 27 connecting to intermediate points ondrive bars 28 and 29 extending between opposite sides of the centralparallelogram defined by the crossed levers. Thus the drive bar 28, byway of example, is coupled as at the points P1 and P2 substantiallymidway between the opposite sides of the central parallelogram definedby the levers 14 and 22. The arrangement is such that a straight linedrawn between the points Pi and P2 will be parallel to the remainingopposite sides defined by the levers 19 and 17 so that collapsing orexpansion of the crossed levers will not -vary the linear distancebetween the points P1 and P2.

It will be noted, however, that the intermediate point 27 of the drivebar 28 to which the lower portion of the hydraulic ram means 26 iscoupled is displaced laterally from the straight line between the pointsP1 and 1 2. The purpose for this lateral spacing will become evident asthe description proceeds.

As shown, the other end of the hydraulic ram means 26. connects to apivot point 36 :which is disposed on one of the remaining sides of thecentral parallelogram defined by the crossed levers. This point 30 isdisplaced slightly from the vertex pivot rod 25 as shown. A suitablesource and pump for the hydraulic fluid is carried on the base [frame asshown at 31.

Withreference now to FIGURE 2, when the upper platform is collapsed intoengagement with the lower base or frame 10 the displaced point 27 towhich the ram means 26 is connected can extend through .the frame 10below the flat configuration formed by the crossed lever structure.There is thus provided room for the ram structure in a fully retractedstate without inhibiting substantially complete collapsing of thecrossed lever configuration.

The points between which the hydraulic rams are'coupled such as 27 and30 are so positioned that a straight line drawn between these pointswill not be parallel to any of the sides of the central parallelogramdefine-d by the crossed levers. This non-parallelism is important sinceif the lines between the points 27 and .30 were parallel to the sides ofthe parallelogram, the distance therebetween would not change duringcollapsing and expansion of the crossed lever structure. By making aline drawn between these points nonparallel or out of parallelism withany of the sides, the distance between these points will vary dependingupon the relative position of the platform '13 to platform 10 andtherefore by applying tension or compression forces between thesepoints, a collapsing or expansion of the crossed levers can be realized.

Referring now to FIGURES 3 to 7, there .are schematically illustratedother positions for the hydraulic ram means which are possible withoutdeparting from the scope and spirit of this invention. Thus, [forexample, a drive bar 62 may extend between the other opposite sides ofthe parallelogram such as defined by the levers 1'9 and 17. Further, thehydraulic ram 26 may have its upper point connected to the vertex pivotthat is, the vertex of the central parallelogram which is verticallyspaced above its diametrically opposite vertex 24.

In 'FIGURE 4 the hydraulic ram 26 is connected between the drive bar 32and the lower vertical vertex 24.

In FIGURE 5 there is illustrated both the drive bar 28 and theadditional drive bar 32 forming a crossed configuration with a connectedportion of the hydraulic ram 26 being coupled to the crossover points ofthe drive bars.

In FIGURE 6 the arrangement is the same as in FIG- URE 5 except that theother end of the hydraulic ram 26 connects to the lower vertex of thecentral parallelogram rather than the upper vertex.

Finally, in FIGURE 7 there is shown the hydraulic ram means 26 connectedbetween the drive bar 28 and a point 33 displaced slightly from thelower vertex point in the same manner that the pivot bar in FIGURE 1 isdisplaced from the upper vertex pivot bar 25.

In all of the embodiments, it is to be noted that there is adisplacement of the intermediate point on the drive bar to which thehydraulic means is connected, this displacement enabling substantiallycomplete collapsing of the crossed lever structure while accommodatingthe hydraulic ram means.

As a consequence of the foregoing, it is possible to provide a portablelift apparatus having all of the advantages and features of my referredto United States patcut with the added feature of being capable of morecomplete collapsing to provide a more compact unit when in collapsedposition.

In addition, by positioning the ram means between the drive bar and oneof the crossed levers making up the central parallelogram configuration,the travel length of the ram means is reduced without changing thetravel distance of the upper platform frame 13.

The entire structure is also simplified and considerably easier tooperate than prior devices as a consequence of the hydraulic ram side byside configuration with the expanding piston rods moving in oppositedirections as shown in FIGURE 1. This arrangement minimizes the spaceoccupied by the ram means. Moreover, the cylinders are connectedtogether hydraulically and are fed by a single hydraulic line from thepump and source 31. Thus, only one pressure is required to expand thestructure for a given load and this pressure is constant. When thepressure is relieved, the structure collapses by gravity. Accordingly,one valve is necessary to apply and release and no skill is required tooperate the mechanism.

Various modifications that fall clearly within the scope and spirit ofthis invention will occur to those skilled in the art. The load liftingapparatus is, therefore, not to be thought of as limited to the fewembodiments set forth merely for illustrative purposes.

What is claimed is:

1. A load lifting apparatus comprising: first and second frames; upperand lower crossed lever means pivotally interposed between said frames,the inner ends of said lever means being pivotally interconnected todefine a central parallelogram portion when said frames are in apartially extended condition with the extending outer ends of said levermeans coupled to said first and second frames, respectively; drive barmeans coupled to opposite sides of said parallelogram; and expansibleram means coupled to an intermediate point on said drive bar meansdisplaced laterally from a straight line drawn between the ends of saiddrive bar means and to a point on one of said crossed lever meansdefining a remaining side of said parallelogram so that said crossedlever means may collapse in scissoring fashion to a substantially flatconfiguration with the displaced intermediate point extending laterallyfrom the plane of said fiat configuration.

2. A load lifting apparatus comprising: a first frame; a second frame;upper and lower lever means pivotally interposed between said firstframe and said second frame, the inner ends of said lever means beingpivotally interconnected to define a central parallogram portion whensaid frames are in a partially extended condition with the extendingouter ends of said lever means coupled to said first and second framesrespectively; a drive bar means having its ends coupled to oppositesides of said portions of said crossed lever means defining said centralparallelogram, a line drawn between the points of coupling of the endsof said drive bar to said opposite sides being parallel to the remainingsides of said parallelogram; and expansible ram means coupled to anintermediate point on said drive bar means and a point on one of saidcrossed lever means defining a remaining side of said parallelogram,such that the longitudinal axis of expansion and contraction of said rammeans is out of parallelism with any of the sides of said parallelogram.

3. An apparatus according to claim 2, in which said intermediate pointis spaced laterally from said line drawn between the points of couplingof the ends of said drive bar means whereby collapsing of said first andsecond frames together can take place until said parallogram issubstantially flat.

4. An apparatus according to claim 2, in which said point on one of saidcrossed lever means defining a remaining side of said parallelogramcoincides with a vertex of said parallelogram in a position in verticalalignment with the diagonally opposite vertex of said parallelogram.

5. An apparatus according to claim 2, including an additional drive barmeans having its ends coupled between the other opposite remaining sidesof said parallelogram, a straight line drawn between the points ofcoupling of said additional drive bar means being parallel to said firstmentioned opposite sides of said parallelogram, said intermediate pointon said first mentioned drive bar means being pivoted to said additionaldrive bar means at its crossover point with said first mentioned drivebar means.

No references cited.

WILLIAM FELDMAN, Primary Examiner.

1. A LOAD LIFTING APPARATUS COMPRISING: FIRST AND SECOND FRAMES; UPPERAND LOWER CROSSED LEVER MEANS PIVOTALLY INTERPOSED BETWEEN SAID FRAMES,THE INNER ENDS OF SAID LEVER MEANS BEING PIVOTALLY INTERCONNECTED TODEFINE A CENTREL PARALLELLOGRAM PORTION WHEN SAID FRAMES ARE IN APARTIALLY EXTENDED CONDITION WITH THE EXTENDING OUT ENDS OF SAID LEVERMEANS COUPLED TO SAID FIRST AND SECOND FRAMES, RESPECTIVELY; DRIVE BARMEANS COUPLED TO OPPOSITE SIDES OF SAID PARALLELLOGRAM; AND EXPANSIBLERAM MEANS COUPLED TO AN INTERMEDIATE POINT ON SAID DRIVE BAR MEANSDISPLACED LATERALLY FROM A STRAIGHT LINE DRAWN BETWEEN THE ENDS OF SAIDDRIVE BAR MEANS AND TO A POINT ON ONE OF SAID CROSSED LEVER MEANSDEFINING A REMAINING SIDE OF SAID PARALLELOGRAM SO THAT SAID CROSS LEVERMEANS MAY COLLAPSE IN SCISSORING FASHION TO A SUBSTANTIALLY FLATCOMFIGURATION WITH THE DISPLACED INTERMEDIATE POINT EXTENDING LATERALLYFROM THE PLANE OF SAID FLAT CONFIGURATION.